During dental treatment, such as a teeth whitening operation, the patient's gums are initially protected using a viscous photo-polymerizable composition in order to form a protective barrier, also termed a gingival barrier. In order to provide a patient's gums with effective protection from the whitening compositions, the composition must be spread uniformly over the gums.
European patent document EP-A-0 956 084 describes an application tip for dental compositions that is formed by a cannula having an application end that is provided with fibrous bristles in order to facilitate spreading of the composition. However, such a tip cannot deposit a wide strip of composition that is uniform in width and thickness.
Patent documents EP-1 810 712 and US-2006/0065677 describe application tips provided with a spatula at their outlet ends to facilitate spreading of the composition. However, in the context of applying a dental composition such as a composition intended to form a gingival barrier, the spatula alone cannot ensure that the composition is deposited effectively on the gums. If the composition is not delivered to the tip outlet in sufficient quantity and with relatively uniform thickness, there is a tendency for the practician to press the spatula harder on the patient's gums in order to compensate for the lack of uniformity of the composition at the tip outlet. On pressing too hard on the spatula, there is a risk that the composition is no longer be deposited continuously onto the patient's gums, thereby leaving parts of the gums exposed. Further, since the gums are fragile, pressing too hard on them is not recommended.